Novel phenol compounds and (co)polymers thereof

ABSTRACT

The present invention relates to A phenol compound according to Formula (I): wherein: R 1  is selected from the group consisting of, optionally substituted, 2-pyridyl, 3-pyridiyl and 4-pyridyl groups, wherein R 1  is at position 2 or 3 of the phenol ring; R 2  is selected from the group consisting of, optionally substituted, 2-pyridyl, 3-pyridiyl, 4-pyridyl and phenyl groups, wherein R 2  is at position 5 or 6 of the phenol ring; and the phenol ring is optionally substituted at one or two positions, independently selected from positions 2, 3, 5 and 6, with a halogen atom or a with an optionally substituted C 6 -C 12  aryl group or an optionally substituted C 1 -C 10  alkyl group. The present invention relates also to (co)polymers comprising the phenol compound according to Formula (I) and membranes and ionic resins comprising said (co)polymers.

FIELD OF THE INVENTION

The present invention relates to novel monomers, (co)polymers prepared from these novel monomers, a process for the preparation of such (co)copolymers and the application of such polymers in membranes having a well-defined selectivity and an improved resistance to harsh environments.

BACKGROUND OF THE INVENTION

In the art, there is still a need for polymer membranes having a well-defined selectivity and an improved resistance to harsh environments. Many separation processes would benefit from the option of being performed at higher temperatures than is currently feasible with state-of-the-art polymer membranes. In particular, anion exchange materials which are often based on polyethylenimine or on trimethylammonium derivatives of polystyrene have limited thermo-oxidative stability.

Highly thermo-oxidatively stable Brønsted basic membranes, after complexation with a strong acid, are also of great potential value in polymer membrane fuel cells. Such higher operating temperatures may lead to simpler fuel cell stack design and allow the use of less pure hydrogen as well as other fuels compared to Nafion®-based fuel cells. Nafion® perfluorosulfonic acid ionomers have the general structure (Butler, G. B.; O'Driscoll, K. F.; Wilkes, G. L. JMS-Rev. Macromol. Chem. Phys. 1994, C34(3), 325-373):

Another disadvantage of Nafion® membranes is that it requires 100% water saturation (i.e. a 100% RH environment) to achieve the required conductivity since water is the proton conducting phase. Hence, operation above 100° C. is virtually impossible due to the water loss from the Nafion® membranes, although an improved performance is expected at higher operating temperatures, e.g. a temperature in the range of about 120° C. up to about 150° C. Hybrid Nafion® membranes are also known in the art but have been applied without much success.

U.S. Pat. No. 5,525,436, U.S. Pat. No. 5,716,727 and U.S. Pat. No. 6,025,085 to R. F. Savinell and Morton H. Litt, incorporated by reference herein, disclose PBI (“PBI” means polybenzimidazole) and similar polymers doped with phosphoric acid. See also J-T Wang, J. S. Wainright, R. F. Savinell and M. H. Litt, J. Appl. Electrochem. 26, 751, 1996 and S. R. Samms, R. Wasmus and R. F. Savinell, J. Electrochem. Soc. 143, 1225, 1996. However, these systems have the disadvantage that they loose phosphoric acid during prolonged use which is presumably related to coagulation of the PBI by water from its phosphoric acid complex (cf. e.g. U.S. Pat. No. 7,045,241 to Akita Hiroshi and Komiya Teruaki, incorporated by reference herein, which discloses the isolation of a PBI composition by pouring its solution in polyphosphoric acid into water).

U.S. Pat. No. 6,723,757 to J. Kerres, A. Ullrich and T. Haring, incorporated by reference, discloses acid-base polymer blend membranes comprising as a first component either a cation exchanging polymer or an anion exchanging polymer and as a second component a polymer comprising one or more nitrogen containing basis moieties. However, pyridine as a nitrogen basic moiety is not disclosed.

U.S. Pat. No. 7,235,320 to G. Calundann, M. J. Sansone, O. Uensal and J. Kiefer, incorporated by reference, discloses a polymer membrane based on polyazoles wherein the azole moiety may be a pyridinylene moiety (structures XVI and XVII).

US 2006/0057449, also to G. Calundann, M. J. Sansone, O. Uensal and J. Kiefer, incorporated by reference, discloses a polymer membrane based on sulphonated polymers comprising recurring benzimidazole units.

US 2007/0141426 to S-w. Choi, H-y Sun, M-j Lee and W-s Jeon, incorporated by reference, discloses systems obtained by crosslinking polybenzimidazole with a benzoxazine-based monomer, wherein the nitrogen atom may be substituted with a 2-pyridyl or 3-pyridyl group.

There is, however, still a need in the art for improved polymer membranes.

SUMMARY OF THE INVENTION

The present invention relates to a phenol compound according to Formula (I):

wherein: R¹ is selected from the group consisting of, optionally substituted, 2-pyridyl, 3-pyridiyl and 4-pyridyl groups, wherein R¹ is at position 2 or 3 of the phenol ring; R² is selected from the group consisting of, optionally substituted, 2-pyridyl, 3-pyridiyl, 4-pyridyl and phenyl groups, wherein R² is at position 5 or 6 of the phenol ring; and the phenol ring is optionally substituted at one or two positions, independently selected from positions 2, 3, 5 and 6, with a halogen atom or a with an optionally substituted C₆-C₁₂ group or an optionally substituted C₁-C₁₀ alkyl group.

The present invention also relates to (co)polymers made of the phenol compound according to Formula (I) and membranes and ionic resins comprising such (co)polymers.

DETAILED DESCRIPTION OF THE INVENTION

The verb “to comprise” as is used in this description and in the claims and its conjugations are used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. In addition, reference to an element by the indefinite article “a” or “an” does not exclude the possibility that more than one of the element are present, unless the context clearly requires that there is one and only one of the elements. The indefinite article “a” or “an” thus usually means “at least one”.

According to the present invention, suitable substituents for alkyl groups, aryl groups, phenyl groups and aryl groups include halogen atoms, in particular fluorine, chlorine and bromine atoms, and C₁-C₆ alkyl groups, wherein the alkyl groups may be linear or branched.

According to the present invention, it is preferred that R² is selected from the group consisting of, optionally substituted, 2-pyridyl, 3-pyridiyl, 4-pyridyl groups. Suitable substituents include halogen atoms, in particular halogen atoms selected from the group consisting of fluorine, chlorine and bromine atoms, and optionally substituted C₆-C₁₂ aryloxy groups. According to the present invention, it is preferred that R¹ and R² are an optionally substituted 3-pyridyl group.

It is also preferred that R¹ is at position 2 of the phenyl ring.

It is furthermore preferred that R² is at position 6 of the phenyl ring.

The present invention also relates to homopolymers or copolymers (further referred to as (co)polymers) which comprises a phenol compound according to the present invention. When the polymer is a copolymer, suitable comonomers include optionally substituted phenol monomers. Suitable substituents for such optionally substituted phenol monomers include halogen atoms, in particular halogen atoms selected from the group consisting of fluorine, chlorine and bromine atoms, optionally substituted C₆-C₁₂ aryl groups and optionally substituted C₁-C₁₀ alkyl groups. The alkyl groups may further be linear or branched, but are preferably not α-branched. The alkyl group may also comprise a cyclic system, provided it comprises at least 3 carbon atoms.

More in particular, the present invention relates to a copolymer according to Formula (II):

wherein: R¹ is selected from the group consisting of, optionally substituted, 2-pyridyl, 3-pyridiyl and 4-pyridyl groups, wherein R¹ is at position 2 or 3 of the phenol ring; R² is selected from the group consisting of, optionally substituted, 2-pyridyl, 3-pyridiyl, 4-pyridyl and phenyl groups, wherein R² is at position 5 or 6 of the phenol ring; the phenol ring bearing R¹ and R² is optionally substituted at one or two positions, independently selected from positions 2, 3, 5 and 6, with a halogen atom, with an optionally substituted C₆-C₁₂ aryl group or a with an optionally substituted C₁-C₁₀ alkyl group; and one or two substituents selected from the group consisting of R³, R⁴, R⁵ and R⁶ are an, optionally substituted phenyl group, whereas the other substituents selected from the group consisting of R³, R⁴, R⁵ and R⁶ are selected from the group of hydrogen, halogen and optionally substituted C₁-C₁₀ alkyl groups.

According to the present invention, it is preferred that R² is selected from the group consisting of, optionally substituted, 2-pyridyl, 3-pyridiyl, 4-pyridyl groups.

It is furthermore preferred that R¹ and R² are an optionally substituted 2-pyridyl group.

It is also preferred according to the present invention that R¹ and R² are an optionally substituted 3-pyridyl group.

Additionally, in the copolymer according to Formula (II), R¹ is preferably at position 2 of the phenyl ring.

It is also preferred that R² is at position 6 of the phenyl ring.

Preferably, R³ and R⁶ are independently selected from the group of optionally substituted phenyl groups. Suitable substituents for the phenyl groups are fluorine and chlorine.

It is also preferred that in the copolymer according to Formula (II) that R⁴ and R⁵ are selected from the group of hydrogen, halogen, optionally substituted C₆-C₁₂ aryl and optionally substituted C₁-C₁₀ alkyl groups. As described above, the alkyl groups may be substituted with one or more halogen atoms, in particular halogen atoms selected from the group consisting of fluorine, chlorine and bromine atoms. The alkyl groups may further be linear or branched, but are preferably not α-branched. The alkyl group may also comprise a cyclic group, provided it comprises at least 3 carbon atoms.

The (co)polymers according to the present invention have generally a number average molecular weight M_(n) of about 7,000 to about 300,000 and a weight average molecular weight M_(w) of about 15,000 to about 1,000,000.

The present invention further relates to a process for polymerising a phenol compound according to Formula (I), wherein the phenol compound, optionally in the presence of a comonomer, is polymerised in the presence of a catalyst. According to the invention, it is preferred that the polymerisation is conducted in a solvent comprising a pyridine compound. More preferably, the solvent is a pyridine compound, in particular 3-chloropyridine.

According to the process of the present invention, it is preferred that the comonomer has the Formula (III):

wherein one or two substituents selected from the group consisting of R³, R⁴, R⁵ and R⁶ are an, optionally substituted phenyl group, whereas the other substituents selected from the group consisting of R³, R⁴, R⁵ and R⁶ are selected from the group of hydrogen, halogen, optionally substituted C₆-C₁₂ aryl groups and optionally substituted C₁-C₁₀ alkyl groups. As described above, the alkyl groups may be substituted with one or more halogen atoms, in particular halogen atoms selected from the group consisting of fluorine, chlorine and bromine atoms. The alkyl groups may further be linear or branched, but are preferably not α-branched. The alkyl group may also comprise a cyclic group, provided it comprises at least 3 carbon atoms.

The catalyst employed in the process according to the present invention preferably comprises a metal, preferably a metal from Group 6-12 of the Periodic Table of Elements (IUPAC version 22 Jun. 2007 and Handbook of Chemistry & Physics 66^(th) Ed., 1985-1986; formerly Groups 6b-2b, cf. Handbook of Chemistry & Physics, 59^(th) 9 Ed., 1978-1979). Most preferably, the catalyst comprises copper, preferably having an oxidation state of at least 1+. Obviously, the catalyst may comprise copper species having different oxidation states.

The (co)polymer according to the present invention is preferably used for the manufacture of membranes, in particular membranes for fuel cells, and ion exchange resins.

EXAMPLES Example 1 Synthesis of 2,6-Bis(3-Pyridyl)Phenol and its Polymerization 2,6-dibromophenyl benzyl ether

2,6-Dibromophenol (29.30 g, 116 mmol) and benzyl bromide (33.14 g, 194 mmol) were dissolved in 2-butanone (300 mL). Potassium carbonate (29.47 g, 213 mmol) was added, and the mixture was stirred for 1.5 hr at reflux temperature. The reaction mixture was cooled to room temperature, filtered, and evaporated to dryness. The remaining viscous oil was subjected to silicagel column chromatography, flushing with n-pentane to remove benzyl bromide, then DCM/n-pentane=1:1 to elute the product, yielding the product as a white crystalline solid (39.32 g, 99%). ¹H-NMR (CDCl₃): δ=7.61 (dd, 2H), 7.54 (d, 2H), 7.41 (m, 3H), 6.90 (t, 1H), 5.04, (s, 2H) ppm.

2,6-bis(3-pyridyl)phenyl benzyl ether

2,6-Dibromophenyl benzyl ether (25.61 g, 74.88 mmol), 3-pyridylboronicacid (20.25 g, 164.7 mmol), aqueous potassium carbonate (233 mL 2 M), and DMF (370 mL) were put together in a 1 liter flask. Oxygen was removed by several vacuum-argon cycles. Then Pd(PPh₃)₄ (5.38 g, 4.65 mmol) was added and the mixture was heated to 85° C. under an argon atmosphere. After 48 hr, the reaction mixture was cooled to rt, and poured into an ice/water mixture (1 L). This was extracted with diisopropylether (3 times 300 mL), and the combined organic layers were dried over MgSO₄, filtered, and the solvent was removed in vacuo, yielding a yellow crystalline solid. Recrystallisation from diethyl ether yielded the product as a white crystalline solid (10.34 g, 41%). The residue was further purified by column chromatography (silicagel, EtOAc/n-pentane=3:2), yielding another 2.60 g (10%) of the product (total yield 51%). ¹H-NMR (CDCl₃): δ=8.80 (s, 2H), 8.59 (d, 2H), 7.93 (dd, 2H), 7.65 (d, 2H), 7.34 (m, 3H), 7.19 (t, 1H), 7.10 (t, 2H), 6.64 (d, 2H), 4.15 (s, 2H) ppm.

In another fraction of the column, the mono-substituted side-product was isolated as a white crystalline solid (6.07 g, 31%). ¹H-NMR (CDCl₃): δ=8.81 (s, 1H), 8.57 (d, 1H), 7.89 (dd, 1H), 7.25-7.40 (m, 8H) 7.06 (t, 2H), 5.09 (s, 2H) ppm.

2,6-bis(3-pyridyl)phenol

2,6-Bis(3-pyridyl)phenyl benzyl ether (16.70 g, 49.35 mmol) was dissolved in MeOH (200 mL). Argon was bubbled through this solution for 10 min to remove oxygen. Then Pd/C (500 mg 5 w %) was added, and the reaction mixture was put into the Parr-reactor and shaken for 16 hr under a hydrogen atmosphere at 80 psi. After the hydrogenation, the resulting precipitate was redissolved by heating to reflux. The hot mixture was filtered over diatomaceous earth, and the filter cake thoroughly washed with hot MeOH. Upon cooling to room temperature, the product crystallized as a white crystalline material (12.25 g, 99%). M.p.=211° C. ¹H-NMR (DMSO): δ=8.74 (d, 2H), 8.55 (dd, 2H), 7.95 (dt, 2H), 7.48 (m, 2H), 7.34 (d, 2H), 7.11 (t, 1H).

Polymerization of 2,6-bis(3-pyridyl)phenol

Cu(I) Cl (2.00 mg, 0.0202 mmol) and TMEDA (2.34 mg, 0.0202 mmol) were dissolved in 3-chloropyridine (2.5 mL). The mixture was heated to 85° C. and air was bubbled through for 10 min. Subsequently 2,6-bis(3-pyridyl)phenol (250 mg, 1.01 mmol) was added. The reaction mixture was heated for 16 hr at 85° C., while maintaining an air flow through the mixture. Then, it was cooled to room temperature and precipitated in diethyl ether (100 mL). The precipitate was washed thoroughly with diethyl ether, and dried in vacuo at 100° C. overnight. The polymer was obtained as a brown powder (220 mg, 88%). [η]=0.35 g/dl (0.1 w % in 95% H₂SO₄).

Example 2 2-(3-pyridyl)phenol

2-(3-pyridyl)phenyl benzyl ether (6.67 g, 25.52 mmol) was dissolved in MeOH (100 mL). Argon was bubbled through this solution for 10 min to remove oxygen. Then Pd/C (350 mg 5 w %) was added, and the reaction mixture was put into the Parr-reactor and shaken for 16 hr under a hydrogen atmosphere at 80 psi. After the hydrogenation, the mixture was filtered over diatomaceous earth, and the colourless solution was evaporated to dryness. The crude product was recrystallized from 2-propanol to yield a white crystalline material (3.54 g, 79%). M.p.=185° C. ¹H-NMR (CDCl₃/MeOD): δ=8.76 (d, 1H), 8.43 (dd, 1H), 8.02 (dt, 1H), 7.39 (m, 1H), 7.21-7.29 (m, 2H), 6.95 (m, 2H). 

1-23. (canceled)
 24. A polymer comprising a phenol compound according to Formula (I):

wherein: R¹ is selected from the group consisting of, optionally substituted, 2-pyridyl, 3-pyridiyl and 4-pyridyl groups, wherein R¹ is at position 2 or 3 of the phenol ring; R² is selected from the group consisting of, optionally substituted, 2-pyridyl, 3-pyridiyl, 4-pyridyl and phenyl groups, wherein R² is at position 5 or 6 of the phenol ring; and the phenol ring is optionally substituted at one or two positions, independently selected from positions 2, 3, 5 and 6, with a halogen atom or a with an optionally substituted C₆-C₁₂ aryl group or an optionally substituted C₁-C₁₀ alkyl group.
 25. The polymer according to claim 24, wherein the polymer is a copolymer.
 26. The copolymer according to claim 25, wherein the polymer is a copolymer according to Formula (II):

wherein: R¹ is selected from the group consisting of, optionally substituted, 2-pyridyl, 3-pyridiyl and 4-pyridyl groups, wherein R¹ is at position 2 or 3 of the phenol ring; R² is selected from the group consisting of, optionally substituted, 2-pyridyl, 3-pyridiyl, 4-pyridyl and phenyl groups, wherein R² is at position 5 or 6 of the phenol ring; the phenol ring bearing R¹ and R² is optionally substituted at one or two positions, independently selected from positions 2, 3, 5 and 6, with a halogen atom, with an optionally substituted C₆-C₁₂ aryl groups or with an C₁-C₁₀ alkyl group; and one or two substituents selected from the group consisting of R³, R⁴, R⁵ and R⁶ are an, optionally substituted phenyl group, whereas the other substituents selected from the group consisting of R³, R⁴, R⁵ and R⁶ are selected from the group of hydrogen, halogen and optionally substituted C₁-C₁₀ alkyl groups.
 27. The copolymer according to claim 26, wherein R² is selected from the group consisting of, optionally substituted, 2-pyridyl, 3-pyridiyl, 4-pyridyl groups.
 28. The copolymer according to claim 26, wherein R¹ and R² are an optionally substituted 2-pyridyl group.
 29. The copolymer according to claim 26, wherein R¹ and R² are an optionally substituted 3-pyridyl group.
 30. The copolymer according to claim 26, wherein R¹ is at position 2 of the phenyl ring.
 31. The copolymer according to claim 26, wherein R² is at position 6 of the phenyl ring.
 32. The copolymer according to claim 26, wherein R³ and R⁶ are independently selected from the group of optionally substituted phenyl groups.
 33. The copolymer according to claim 26, wherein R⁴ and R⁵ are selected from the group of hydrogen, halogen, optionally substituted C₆-C₁₂ aryl groups and C₁-C₁₀ alkyl groups.
 34. A process for preparing a polymer according to claim 24 comprising polymerizing a phenol compound according to Formula (I), optionally in the presence of a comonomer, in the presence of a catalyst.
 35. The process according to claim 34, wherein the comonomer has the Formula (III):

wherein one or two substituents selected from the group consisting of R³, R⁴, R⁵ and R⁶ are an, optionally substituted phenyl group, whereas the other substituents selected from the group consisting of R³, R⁴, R⁵ and R⁶ are selected from the group of hydrogen, halogen and optionally substituted aryl or C₁-C₁₀ alkyl groups.
 36. The process according to claim 35, wherein the catalyst comprises copper.
 37. The process according to claim 35, wherein the polymerisation is conducted in a solvent comprising a pyridine compound.
 38. A membrane comprising the polymer according to claim
 24. 39. A fuel cell comprising the membrane according to claim
 38. 40. An ionic resin comprising the polymer according to claim
 24. 